Optical disc clamp mechanism and adapter for use in an optical disc apparatus

ABSTRACT

In a clamp mechanism, an adapter, and an optical disc apparatus for compatibly playing back the MD and CD having different centering hole diameters and reference heights, a first clamp mechanism has a taper cone section for both an MD and a CD, while a second clamp mechanism has an MD turntable and a CD clamper which is driven in contact with the MD turntable while clamping the CD. The adapter is a disc which has a hole having the same inner diameter as that of the centering hole of the MD and a thickness of 0.8 mm, the adapter to be attached to the CD. A first optical disc apparatus has an MD spindle motor and a CD spindle motor, and an optical system including an objective lens is arranged on a straight line that connects both the spindle motors. A second optical disc apparatus has a spindle motor having an MD turntable and a CD turntable at both its ends.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical disc apparatus compatiblewith either of a mini disc (referred to as, "MD" hereinafter) and acompact disc (referred to as "CD" hereinafter) serving as data recordingmedia for music, video, code data, and the like.

2. Description of the Prior Art

Conventionally, a CD has been popularly used as an optical disc datarecording medium mainly for recording music data. In recent years, an MDhas been developed as an optical disc data recording medium capable ofeasily recording data thereon.

The following describes MD and CD turntables of conventional MD and CDplayers with reference to the attached drawings.

FIGS. 8 (a), 8(b) and 8 (c) show a clamping operation of an MD turntableof a conventional MD player, while FIGS. 9 (a), 9 (b) and 9 (c) show aclamping operation of a CD turntable of a conventional CD player.

Reference is first-made to an MD turntable in connection with FIGS. 8(a) to 8 (c), where FIGS. 8 (a) and 8 (b) show a pre-clamping condition,while FIG. 8 (c) shows a post-clamping condition. In FIGS. 8 (a) to 8(c), an MD 100 is composed of an approximately disc-shaped transparentsubstrate 1 having a thickness of 1.2 mm and a magnetic thin plate 2which is rigidly adhered to the substrate 1. The substrate 1 has itsupper surface serving as a data recording surface 1a and has its lowersurface serving as a ring-shaped clamp area 1b which is verticallyoffset by 0.8 mm, with a centering hole 1c having a diameter of 11 mmformed at the center of the substrate 1. Although the MD 100 is normallyreceived in a cartridge, such a cartridge is not shown herein.

Reference numeral 200 denotes an MD turntable for clamping the MD 100.Reference numeral 6 denotes a rotary shaft of a spindle motor (notshown) for generating a rotational torque. Reference numeral 3 denotes aflange-shaped disc receiving section to be put in contact with the clamparea 1b when the MD 100 is clamped. Reference numeral 4 denotes a tapercone section composed of a part of a sphere, which is fitted verticallyand slidably in a recess 8 formed in the disc receiving section 3.Reference numeral 7 denotes a spring member for applying a biasing forceto the taper cone section 4 to be biased upward. Reference numeral 5denotes a magnet clamper which is composed of a torus-shaped magnet 5aand a yoke 5b. The magnet clamper 5 is rigidly fixed to a portion aroundthe center of the disc receiving section 3 in a position closer to theMD 100. The torus-shaped magnet 5a has its upper portion magneticallyoriented toward the north pole. The yoke 5b is made of a magneticsubstance, which surrounds the magnet 5a except for the top surface ofthe magnet 5a facing the MD 100.

The following describes the operation of the conventional MD turntablehaving the above-mentioned construction.

When the MD 100 is moved closer to the MD turntable 200 from thecondition shown in FIGS. 8 (a) and 8 (b), the magnet clamper 5 attractsthe magnetic thin plate 2 of the MD 100 due to its magnetic force. Thesubstrate 1 is put in contact with the taper cone section 4 at its innerperipheral edge of the centering hole 1c. In the above place, themagnetic force of the magnet 5a further attracts the MD 100 downward,and therefore a downward force is applied to the taper cone section 4.On the other hand, since the magnet clamper 5 is rigidly fixed to thedisc receiving section 3 while the taper cone section 4 is verticallyslidable with respect to the disc receiving section 3, the spring member7 which is biasing upward the taper cone section 4 is elasticallycompressed to depress the taper cone section 4 downward. The downwardmovement of the taper cone section 4 continues until the clamp area 1bis put in contact with the disc receiving section 3, and thus the MD 100is completely clamped as shown in FIG. 8 (c).

In the condition where the disc clamping is completed, the level of thedata recording surface 1a is defined by the disc receiving section 3,while the position of the MD 100 in the direction of the plane of thedisc is defined by the contact of the edge of the centering hole 1c withthe taper cone section 4. The height of the data recording surface 1afrom the surface of the disc receiving section 3 is 0.8+1.2=2.0 mm asshown in FIG. 8 (a).

Then reference is made to the CD turntable in connection with FIGS. 9(a) to 9 (c), where FIGS. 9 (a) and 9 (b) show a pro-clamping condition,while FIG. 9 (c) shows a post-clamping condition. In FIGS. 9 (a) to 9(c), reference numeral 300 denotes a CD which is composed of anapproximately disc-shaped transparent substrate 11 having a thickness of1.2 mm. The substrate 11 has its top surface serving as a data recordingsurface 11a. In the center position of the substrate 11, there is formeda centering hole 11c having a diameter of 15 mm.

Reference numeral 400 denotes a CD turntable for clamping the CD 300.Reference numeral 16 denotes a rotary shaft of a spindle motor (notshown) for generating a rotational torque. Reference numeral 13 denotesa flange-shaped disc receiving section to be put in contact with thelower surface of the CD 300 when the CD 300 is clamped, where the discreceiving section 13 has a recess 13a and a hub-like projection 13bformed therein. Reference numeral 14 denotes a taper cone section whichis composed of a part of a sphere vertically and slidably fit in therecess 13a formed in the disc receiving section 13. Reference numeral 17denotes a spring member for applying an upward biasing force to thetaper cone section 14.

Reference numeral 18 denotes a disc pressing holder having a recess 18aformed in the center portion thereof. The disc holder 18 is loaded froma CD player and moved down onto the CD 300 so as to be rotatable aroundthe motor shaft 16 when the CD 300 is clamped on the CD turntable 400.

The following describes the clamping operation of the CD turntablehaving the above-mentioned construction.

When the CD 300 is moved closer to the CD turntable 400 from thecondition as shown in FIGS. 9 (a) and 9 (b), the substrate 11 is engagedin contact with the taper cone section 14 at the inner peripheral edgeof the centering hole 11c. In the above place, the disc pressing holder18 is moved down onto the CD 300 to depress the CD 300 downward.Therefore, a downward force is applied to the taper cone section 14. Onthe other hand, since the taper cone section 14 is vertically slidablein the recess 13a of the disc receiving section 13, the spring 17biasing upward the taper cone section 14 is elastically compressed todepress the taper cone section 14 downward. When the disc pressingholder 18 is further moved downward, the hub-like projection 13b of thedisc receiving section 13 is engaged with the recess 18a of the discpressing holder 18, thereby centering the disc pressing holder 18 withrespect to the motor shaft 16. The downward movement of the taper conesection 14 due to depression of the disc pressing holder 18 is continueduntil the CD 300 is put in contact with the disc receiving section 13,and thus the CD 300 is completely clamped as shown in FIG. 9 (c).

In the condition where the disc clamping is completed, the level of thedata recording surface 11a is defined by the disc receiving section 13,while the position of the CD 300 in the direction of the plane of thedisc is defined by the engagement of the taper cone section 14 put incontact with the centering hole 11c. The height of the data recordingsurface 11a from the surface of the disc receiving section 13 isapproximately equal to the thickness of 1.2 mm of the substrate 11.

The aforementioned constructions, however, have the following problems.

Since the MD 100 and the CD 300 are subjected to a laser beam reflectiontype playback operation, it is technically easy to read data of eitherthe MD and the CD by means of an identical single optical head. Wheneither the MD and CD can be subjected To a playback operation by meansof an identical disc apparatus, a great cost reduction and the likemerits can be achieved.

However, the clamping means of the MD and CD significantly differ fromeach other as described above, and therefore no conventional single discdrive unit can compatibly play back the discs of MD and CD. Forinstance, the diameter of the centering hole 1c of the MD 100 is 11 mm,whereas the centering hole 11c of the CD 300 is 15 mm. The MD 100 isclamped by utilizing the magnetic force of the magnet clamper 5, whereasthe CD 300 is held by utilizing an external application force of thedisc pressing holder 18. Moreover, since the MD 100 is stored in acartridge, it is impossible to externally hold to clamp the MD 100.Furthermore, as described for the conventional example, the height ofthe data recording surface 1a from the disc receiving section 3 of theMD is 2.0 mm, whereas the height of the data recording surface 11a fromthe disc receiving section 13 of the CD is 1.2 mm.

Therefore, it has been difficult for the conventional disc apparatus orclamping means to compatibly play back either of the MD and the CD bymeans of an identical disc drive unit because the clamping architecturesof the discs are fundamentally different from each other. Therefore, inorder to provide a hybrid audio apparatus such as a radio cassetteplayer/recorder with the capability of compatibly playing back the MDand CD, special drive units are necessary for each of the discs. Theabove fact results in increasing the size and weight of the apparatus aswell as increasing the cost.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made in order to solve theaforementioned problems, and an essential objective of the presentinvention is to provide an optical disc clamp mechanism, an adapter, andan optical disc apparatus capable of compatibly playing back either ofan MD and a CD.

In order to achieve the aforementioned objective, a first optical discclamp mechanism of the present invention comprises: an approximatelycircular disc receiving section which has at least an outer diameterbeing greater than the outer diameter of the centering hole of the CDand smaller than the outer diameter of the clamp area of the MD andwhich is to be put in contact with the reference surface of either ofthe MD and the CD; an approximately cone or spherical shaped first tapercone section for the MD, which is arranged peripherally inside the discreceiving section and elastically supported on the disc receivingsection in the direction of a rotary shaft of a spindle motor as engagedwith the centering hole of the MD; and an approximately cone orspherical shaped second taper cone section for the CD, which iselastically supported on the disc receiving section in the direction ofthe rotary shaft of the spindle motor as engaged with the centering holeof the CD. The first taper cone section for the MD and the second tapercone section for the CD are elastically depressed toward the spindlemotor by the inner peripheral edge of the centering hole of the MD orthe centering hole of the CD when the MD or the CD is loaded on the discreceiving section. The first taper cone section for the MD is arrangedperipherally inside the second taper cone section for the CD anddisposed substantially farther away from the spindle motor, while thesecond taper cone section for the CD is so arranged as to prevent itfrom interfering with the MD which is loaded on the disc receivingsection.

An optical disc clamp mechanism is provided for use in an optical discapparatus which executes at least playback of an MD and a CD compatibly.The optical disc clamp mechanism comprises a turntable for the MDprovided at an end of a motor rotary shaft; and a CD clamper which isarranged approximately in parallel with the MD turntable so as to facethe MD turntable at least in a condition that the CD clamper isrotatably supported around the rotary shaft separated therefrom. The CDclamper further includes centering means for centering the CD byengagement in contact with a centering hole of the CD, and couplingmeans for coupling the CD with the CD clamper by engagement in contactwith the centering hole and either of both surfaces of the CD. A spacersection is provided and has a CD clamping area the level of whichprotrudes from the plane of the light-receiving surface of the CDcoupled with the CD clamper by the coupling means to be put in contactwith the surface of the disc receiving section of the MD turntable whenthe CD clamper is clamped on the MD turntable. CD clamper centeringmeans is provided for centering the CD clamper with respect to the MDturntable as put in contact with the centering mechanism of the MDturntable. The spacer section is formed so that a distance from a CDclamp area to the data recording surface of the CD in the direction ofthe axis of the rotary shaft and a distance from the MD clamp area tothe data recording surface of the MD in the direction of the axis of therotary shaft are approximately equal to each other.

An adapter is provided for use in an optical disc apparatus for at leastplaying back an MD and a CD compatibly. The optical disc apparatus hasan MD turntable provided at an end of a motor rotary shaft. The adaptercomprises a clamp mechanism approximately the same as the clampmechanism of the MD, a centering means for centering the CD with theadapter by engagement in contact with a centering hole of the CD, andcoupling means for coupling the CD with the adapter by engagement incontact with at least one of the centering hole and both surfaces of theCD. A spacer section protrudes from the plane of the light-receivingsurface of the CD coupled with the adapter by the coupling means andwhich includes a CD clamping area to be put in contact with the discreceiving surface of the MD turntable when clamped on the MD turntable.Adapter centering means is provided for centering the adapter withrespect to the MD turntable as put in contact with the centeringmechanism of the MD turntable. The spacer section is formed so that adistance from an adapter clamp area to the data recording surface of theCD in the direction of the axis of the rotary shaft and a distance fromthe MD clamp area to the data recording surface of the MD in thedirection of the axis of the rotary shaft are approximately equal toeach other.

An optical disc apparatus comprises an optical head having at least anobjective lens for executing at least playback of an MD and a CD byapplying a laser beam onto each of the discs, an MD turntable having anMD disc receiving section, which is operatively coupled to an MD rotaryshaft. A CD turntable is provided and has a CD receiving section, whichis operatively coupled to a CD rotary shaft arranged approximately inparallel with the MD rotary shaft. The objective lens is arranged in aposition on a straight line that connects the MD rotary shaft and the CDrotary shaft, and the level of the MD disc receiving section is advancedby a distance of 0.8 mm below the level of the CD receiving section. TheMD turntable is arranged in a position where the MD turntable does notinterfere with the CD loaded on the CD turntable, so that the objectivelens cpmpatibly accesses either of the MD and CD in the radial directionof each disc.

An optical disc apparatus comprises a base means, a single optical headwhich has at least an objective lens for executing at least playback ofan MD and a CD by applying a laser beam onto each of the discs to accessin a radial direction of each disc, and a spindle motor provided with anMD turntable at one end of its rotary shaft and a CD turntable at theother end of its rotary shaft. The spindle motor has a function offorwardly and reversely rotating its rotary shaft. A pivot mechanism isprovided and has a pivot shaft extending approximately perpendicular tothe rotary shaft of the spindle motor to support the spindle motorpivotally around the pivot shaft with respect to the base as mounted ina position between the spindle motor and the base. Pivot support meanssupports a pivotal movement of the spindle motor around the pivot shaftin either a first condition where the rotary shaft of the spindle motoris approximately in parallel with a direction of the laser beam from theobjective lens and a direction directed from the spindle motor to the MDturntable is approximately equal to the direction of the laser beam, ora second condition where the rotary shaft of the spindle motor isapproximately in parallel with the direction of the laser beam from theobjective lens and a direction directed from the spindle motor to the CDturntable is approximately equal to the direction of the laser beam. Thepivot shaft is arranged in position so that the distance from theobjective lens to the data recording surface of the MD in a conditionwhere the MD is loaded on the MD turntable in the first condition isapproximately equal to the distance from the objective lens to the datarecording surface of the CD in a condition where the CD is loaded on theCD turntable in the second condition.

According to a feature of the first optical disc clamp mechanism of thepresent invention, the first and second taper cone sectionsindependently effect the centering of the MD and CD having differentcentering hole diameters to allow either of the MD and the CD to becentered compatibly.

According to a feature of the second optical disc clamp mechanism of thepresent invention, the CD clamper having the CD clamped thereon can beclamped on the MD turntable. Furthermore, the data recording surface ofeither of the MD and the CD can be put at an equal distance from thesurface of the disc receiving section.

According to a feature of the adapter of the present invention, theadapter having the CD clamped thereon can be clamped on the MD turntableto allow the optical disc apparatus to have no special construction forthe CD. Furthermore, the data recording surface of either the MD and theCD can be put at an equal distance from the surface of the discreceiving section.

According to the first optical disc apparatus of the present inventionhaving the aforementioned construction, the objective lens can accesseither of the MD and the CD in the radial direction of each disc, andthe data recording surface of each of the MD and the CD can be put at anequal distance from the objective lens, which allows either of the discsto be played back utterly in the same condition.

According to the second optical disc apparatus of the present inventionhaving the aforementioned construction, the MD and CD can be driven byone spindle motor, and the data recording surface of either the MD andthe CD can be treated equally in view of the objective lens.

As described above, the present invention can provide an optical discclamp mechanism, and an adapter for use in an optical disc apparatusallowing play back of either of the MD and the CD by means of a singleoptical head and single drive unit. This provides a number of advantagessuch as cost reduction, space savings, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention willbecome apparent from the following description taken in conjunction withthe preferred embodiment thereof with reference to the accompanyingdrawings, in which:

FIG. 1 (a) is a sectional view of a clamp mechanism in accordance with afirst embodiment of the present invention;

FIG. 1 (b) is a sectional view for explaining the operation of the clampmechanism of the first embodiment when clamping an MD;

FIG. 1 (c) is a sectional view for explaining the operation of the clampmechanism of the first embodiment when clamping a CD;

FIG. 2 is a sectional view of a clamp mechanism in accordance with asecond embodiment of the present invention;

FIG. 3 is a partially-enlarged sectional view of the clamp mechanism ofthe second embodiment of the present invention;

FIG. 4 is a sectional view for explaining the operation of the clampmechanism of the second embodiment when clamping a CD;

FIG. 5 (a) is a sectional view of an adapter in accordance with a thirdembodiment of the present invention;

FIG. 5 (b) is a sectional view for explaining the operation of theadapter of the third embodiment having a CD attached thereto;

FIG. 5 (c) is a sectional view for explaining the operation of theadapter of FIG. 5 (b) when clamped to an MD turntable;

FIG. 6 (a) is a plan view of an optical disc apparatus in accordancewith a fourth embodiment of the present invention;

FIG. 6 (b) is a side sectional view of the optical disc apparatus of thefourth embodiment;

FIG. 7 is an explanatory view of an optical disc apparatus in accordancewith a fifth embodiment of the present invention;

FIGS. 8 (a), 8 (b) and 8 (c) are sectional views for explaining aclamping operation of a conventional MD turntable; and

FIGS. 9 (a), 9 (b) and 9 (c) are sectional views for explaining aclamping operation of a conventional CD turntable.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before the description proceeds, it is to be noted that, since the basicstructures of the present embodiments are similar to those of theconventional ones, like parts are designated by the same referencenumerals throughout the drawings and the redundant explanation thereofis omitted here.

First Embodiment

The following describes an optical disc clamp mechanism in accordancewith a first embodiment of the present invention with reference to theattached drawings.

FIGS. 1 (a) through 1 (c) show an optical disc clamp mechanism inaccordance with the first embodiment of the present invention, whereFIG. 1 (a) shows a condition where no disc is loaded, FIG. 1 (b) shows acondition where an MD is loaded, and FIG. 1 (c) shows a condition wherea CD is loaded.

In FIGS. 1 (a) through i (c), a magnet clamper 5, a rotary shaft 6 of aspindle motor (not shown), and a spring 7 are the same as those of theconventional example. Reference numeral 23 denotes a disc receivingsection which has the same function as those of the disc receivingsections 3 and 13 in the conventional example. Reference numeral 24denotes a taper cone section including a first taper cone 24a positionedat the inner peripheral side and a second taper cone 24b positioned atthe outer peripheral side. The first taper cone 24a is protruded fromthe second taper cone 24b. The taper cone section 24 is fit in a recess23a of the disc receiving section 23 so as to be slidable in a directionin parallel with the rotary shaft 6. The spring 7 applies a biasingforce for biasing the taper cone section 24 upward. The magnet clamper 5is secured at an upper portion around the center of the disc receivingsection 23 in the same manner as in the conventional example. In FIGS. 1(b) and 1 (c), the MD 100 and the CD 300 are the same as those of theconventional example.

The following describes the operation of the optical disc clampmechanism having the above-mentioned construction.

First, reference is made to a case where the MD 100 is clamped inconnection with FIG. 1 (b).

When the MD 100 is moved closer to the disc receiving section 23, themagnet clamper 5 attracts a thin plate shaped magnetic member 2 of theMD 100 due to its magnetic force. The substrate 1 is put in contact withthe first taper cone 24a of the taper cone section 24 at the innerperipheral edge of the centering hole 1c while being not in contact withthe other portion of the taper cone section 24. Subsequently, the tapercone section 24 is depressed downward against the biasing force of thespring 7 until the clamp area 1b is put in contact with the top edge ofthe disc receiving section 23 in the same manner as in the conventionalexample, and consequently the MD 100 is completely clamped on theturntable 200 as shown in FIG. 1 (b).

In the condition that the clamping of the MD 100 is completed, the levelof the data recording surface 1a is defined by the disc receivingsection 23, and the position of the MD 100 in the direction of the planeof the disc is defined by the first taper cone 24a of the taper conesection 24 engaged in contact with the inner peripheral edge of thecentering hole 1c. In this condition, only the first taper cone 24a ofthe taper cone section 24 is put in contact with the centering hole 1cof the MD 100, and the other portion of the taper cone section 24 is notput in contact with the MD 100. In more detail, when the MD is attachedto the disc receiving section 23, the second taper cone 24b is preventedfrom contacting with the MD by defining a clearance 23c. The height ofthe data recording surface 1a from the disc receiving section 23 is0.8+1.2=2.0 mm in the same manner as in the conventional example asshown in FIGS. 8 (a) and 8 (b).

Then, the following describes the operation in he case where the CD 300is clamped with reference to FIG. 1 (c).

When the CD 300 is moved closer to the disc receiving section 23, thesubstrate 11 is put in contact with the second taper cone 24b of thetaper cone section 24 at the inner peripheral edge of the centering hole11c, while the substrate 11 is not put in contact with the other portionof the taper cone section 24. At this moment, the disc pressing holder(not shown), which is the same as the conventional disc holder 18, movesdown onto the CD 300 to depress the CD 300 downward. Subsequently, thetaper cone section 24 is further depressed downward until the CD 300 isput in contact with the disc receiving section 23 in the same manner asin the conventional example, and consequently the CD 300 is completelyclamped as shown in FIG. 1 (c).

In the condition where the clamping of the CD is completed, the level ofthe data recording surface 11a is defined by the disc receiving section23, while the position of the CD 300 in the direction of the plane ofthe disc is defined by the contact of the second taper cone 24b of thetaper cone section 24 with the peripheral edge of the centering hole11c. In this condition, only the second taper cone 24b is put in contactwith the centering hole 11c of the CD 300, and the other portion of thetaper cone section 24 is not put in contact with the CD 300. The heightof the data recording surface 11a from the disc receiving section 23 is1.2 mm in the same arrangement as in the conventional example as shownin FIGS. 9 (a) and 9 (b).

According to the present embodiment as described above, by providing thefirst taper cone 24a which is to be put in contact only with the MD 100and the second taper cone 24b which is to be put in contact only withthe CD 300, the first and second taper cones 24a and 24b independentlyeffect the cantering of the MD 100 and the CD 300 respectively havingdifferent centering hole diameters to allow either of the discs to becentered. Furthermore, by providing the magnet clamper 5 for the MD 100,the construction of magnetically clamping the MD 100 and theconstruction of externally pressing and holding the CD 300 can becompatibly achieved.

Second Embodiment

The following describes an optical disc clamp mechanism in accordancewith a second embodiment of the present invention with reference to theattached drawings.

The purpose of the present embodiment is to achieve an optical discclamp mechanism (or adapter) where either of the MD and the CD can becompatibly clamped and the distance from the disc receiving section tothe data recording surface of each disc is identical.

FIGS. 2 through 4 show an optical disc clamp mechanism in accordancewith the second embodiment of the present invention, where FIG. 2 showsa condition when a CD is loaded, FIG. 3 shows the detail of a portion ofthe clamp mechanism, and FIG. 4 shows a condition when the clampmechanism is loaded on an MD turntable.

in FIGS. 2 through 4, the CD 300 and the MD turntable 200 are the sameas those in the conventional example. Reference numeral 31 denotes athin plate shaped magnetic member which has a slightly differentmechanism configuration from that of the conventional example, however,it has the same magnetic property.

Reference numeral 30 denotes a CD clamper having a disc-shaped (annular)CD receiving surface 30a for receiving the data recording surface 11a ofthe CD 300 and a hollow cylindrical spacer section 30i which protrudesdownward from the CD receiving surface S0a by 2.0 mm. The spacer section30i is provided with a cylindrical section CD centering 30b having itsouter diameter slightly smaller than that of the centering hole 11c ofthe CD 300. A hole opening 30c is formed at the center of the CDcentering section 30b, where the hole diameter is the same as that ofthe centering hole 1c of the MD 100 (i.e., 11 mm). Reference numeral 30ddenotes an annular contact surface to be put in contact with the discreceiving section 3 of the MD turntable 200, the contact surface beingprovided at the bottom end of the CD centering section 30b. Referencenumeral 30f denotes an annular magnetic member fixation surface to whichthe magnetic member 31 is rigidly fixed.

As shown in FIG. 3, on the peripheral side surface of the CD centeringsection 30b are formed four steel ball housings 30g arranged at regularangular intervals of 90°. A distance H1 from the CD receiving surface30a to the center axis of each steel ball housing 30g is designed to begreater than 1.2 mm (i.e., thickness of the substrate 11). In each steelball housing 30g, a spring 33 for the steel ball and a steel ball (oroptical disc coupling element) 32 in this order are inserted. The steelball 32 has an outer diameter which is slightly smaller andapproximately equal to the inner diameter of the steel ball housing 30gto be slidable with respect to the inner surface of the steel ballhousing 30g.

The spring 33 for the steel ball biases the steel ball 32 toward theexternal surface of the CD centering section 30b. However, a pawlsection 30h having an inner diameter smaller than the outer diameter ofthe steel ball 32 is formed at the peripheral portion of the outlet ofthe steel ball housing 30g in the vicinity of the external surface ofthe CD centering section 30b. Therefore, the steel ball 32 is preventedfrom dropping out of the steel ball housing 30g, but a part of the steelball 32 protrudes from the external surface of the CD centering section30b due to the inner diameter of the pawl section 30h. As shown in FIG.3, a distance H2 between the CD receiving surface 30a and the curved tipend of the pawl section 30h is designed to be slightly smaller than thethickness 1.2 mm of the substrate 11.

As shown in FIGS. 2 to 4, reference numeral 34 denotes a support: membersupported on a vertical movement mechanism (not shown) of the discapparatus. The support member 34 has an inverted T-shapedcross-sectional configuration composed of a disc section 34a at thebottom end and a cylindrical section 34b which extends from the verticalmovement mechanism of the disc apparatus and is integrally connected tothe disc section 34a. The CD clamper 30 has a construction such that itencloses the disc section 34a with a clearance therebetween for allowingboth the members to be kept out of contact with each other. Referencenumeral 30e denotes a clearance hole through which the cylindricalsection 34b of the support member 34 extends 20 as to be kept apart fromthe CD clamper 30 by a specified distance. The clearance hole has a holediameter smaller than the outer diameter of the disc section 34a andgreater than the outer diameter of the cylindrical section 34b.Therefore, the CD clamper 30 does not fall off the support member 34.

The following describes the operation of the optical disc clampmechanism having the above-mentioned construction.

First, the CD 300 is made to approach the CD clamper 30 from below insuch a manner that the data recording surface 11a face the CD receivingsurface 30a and the CD centering section 30b of the CD clamper 30 isinserted into the centering hole 11c of the CD 300. The steel ball 32protrudes from the external surface of the CD centering section 30b;however, since the steel ball 32 is slidable in the steel ball housing30g, the steel ball 32 is pushed by the peripheral edge of the centeringhole 11c when a sufficient force for inserting the CD 300 is applied.Then the spring 33 biasing for the steel ball is elastically compressedby a horizontal component of the applied force to move the steel ball 32deep into the steel ball housing 30g, so that the steel ball 32 isretracted from the CD centering section 30b to allow the CD 300 to becontinuously inserted.

When the disc insertion is continued, since the distance H1 from thecenter axis of the steel ball housing to the CD receiving surface 30a isgreater than 1.2 mm and the substrate 11 has a thickness of 1.2 mm asshown in FIG. 3, the steel ball 32 protrudes again from the externalsurface of the CD centering section 30b before the data recordingsurface 11a reaches the CD receiving surface 30a.

In the condition where the CD 300 is completely loaded on the CD clamper30, the data recording surface 11a is in contact with the CD receivingsurface 30a as shown in FIGS. 2 and 3. Since the distance H2 from the CDreceiving surface 30a to the curved end of the pawl section 30h isdesigned to be slightly smaller than 1.2 mm, the steel ball 32 does notcontact with the pawl section 30h but rather contacts with the lowerperipheral edge of the centering hole 11c as shown in FIG. 3 in thiscondition. In more detail, the biasing force of the spring 33 acts onthe CD 300 by way of the steel ball 32 to push the data recordingsurface 11a against the CD receiving surface 30a to thereby constitute acoupling means to couple the CD to the CD clamper 30 and determine theposition and effect the centering of the disc, due to the balanceprovided by the four springs 33 for four steel balls.

When the vertical movement mechanism of the disc apparatus moves down tomake the support member 34 approach the MD turntable 200, the CD clamper30, which has completed the clamping of the CD 300 and is connectedslidably to the support member 34, approaches the MD turntable 200 asshown in FIG. 4. The CD clamper 30 has the magnetic member 31 fixedthereto in the same manner as the magnetic member 2 provided for the MD100, and has a centering hole 30c formed therein with its diameter thesame as that of the centering hole 1c of the MD 100. Therefore, themagnetic member 31 is attracted to the magnet clamper 5 due to itsmagnetic force in the same manner as in the conventional example. Thenthe centering hole 30c is centered by the taper cone section 4, and thesurface 30d is put in contact with the disc receiving section 3 tocompletely clamp the CD 300 to the MD turntable 200.

In the, condition where the clamping is completed, the height of thedata recording surface 11a is defined by the disc receiving section 3and the distance from the contact surface 30d to the CD receivingsurface 30a. The position of the CD 300 in the direction of the plane ofthe disc is regulated by the contact of the centering hole 30c with thetaper cone section 4, and by the contact between the steel ball 32 andthe centering hole 11c. In the above condition, the support member 34 isnot in contact with the CD clamper 30.

The distance from the disc receiving section 3 to the data recordingsurface 11a is 2.0 mm which is approximately equal to the distance fromthe surface 30d to the CD receiving surface 30a. The above value ofdistance is equal to the distance 2.0 mm from the disc receiving section3 to the data recording surface 1a of the MD 100 as in the descriptionfor the conventional example shown in FIGS. 8 (a) and 8 (b).

The operation of clamping the MD 100 onto the MD turntable 200 isperformed in the same manner as that in the conventional example, andtherefore no description is provided therefor.

According to the present embodiment as described above, the CD clamper30 having the CD 300 clamped therewith can be clamped on the MDturntable 200 by providing a clamp mechanism including the same magnetclamp 31 as that of the MD 100, where the CD clamper 30 is provided withthe CD receiving surface 30a for receiving the data recording surface11a of a CD, the contact surface 30d to be put in contact with the discreceiving section 3 of the MD turntable 200, the spring 33 and the steelball 32 (which constitute a coupling means) for centering the CD 300 andcoupling the CD 300 to the CD clamper 30 by pressing the CD against theCD receiving surface 30a, and where the distance from the contactsurface 30d to the CD receiving surface 30a is made 2.0 mm equal to thedistance from the clamp area 1b of the MD 100 to the data recordingsurface 1a. Furthermore, the data recording surface 1a of the MD 100 andthe data recording surface 11a of the CD 300 are put at an equaldistance from the disc receiving section 3. Therefore, the datarecording surface 1a and the data recording surface 11a are put at anequal distance from the optical head to allow for the reading of datafrom either of the MD and the CD by a single optical head without anytechnical problem.

Although four steel ball housings 30g each for storing a steel ball 32and spring 33 are employed and arranged at regular angular intervals of90° in the present embodiment, it is also permitted to use any number ofsteel ball housings 30g for the springs and steel balls provided thatnot fewer than three steel ball housings are arranged at approximatelyregular angular intervals.

Although the elastic restoration force of the spring 33 for the steelball is used to press the CD 300 against the CD receiving surface 30a toeffect the centering of the CD in the present embodiment, any othermethod may be adopted as the centering means instead of providing steelball housings.

Third Embodiment

The following describes an adapter in accordance with a third embodimentof the present invention with reference to the attached drawings.

The purpose of the present embodiment is to achieve an adapter to beattached to a CD, allowing the CD to be loaded on the MD turntable whileensuring an identical distance from the disc receiving section to thedata recording surface of each disc.

FIGS. 5 (a) through 5 (c) show an adapter in accordance with the thirdembodiment of the present invention, where FIG. 5 (a) shows the adapter,FIG. 5 (b) shows a condition having a CD attached on the adapter, andFIG. 5 (c) shows a condition of the adapter with the CD loaded on the MDturntable.

In FIG. 5 (a) through 5 (c), the CD 300 and the MD turntable 200 are thesame as those of the conventional example. Reference numeral 41 denotesa magnetic member substantially the same as the magnetic member 2 in theconventional example. Reference numeral 40 denotes an approximatelydisc-shaped adapter which has a thickness of 0.8 mm and is made of, forexample, resin. The adapter 40 has a CD receiving surface 40a at itsupper portion to which the light-receiving surface 11b of the CD 300 isattached as shown in FIGS. 5 (a) and 5 (b). The other surface 40dopposite from the CD receiving surface 40a is to be put in contact withthe disc receiving section 3 of the MD turntable 200. At the center ofthe adapter 40, a centering hole 40c is formed having the same diameterof 11 mm as that of the centering hole 1c of the MD 100.

On the CD receiving surface 40a, there are integrally molded foursquare-pole-shaped elastic projections 40b which are approximatelyvertically extended and arranged at regular angular intervals of 90°concentrically with the centering hole 40c. The elastic projections 40bcan be elastically deformed in a direction in parallel with the CDreceiving surface 40a. The outer diameter of the intersections of theelastic projections 40b and the CD receiving surface 40a is 15 mm whichis the same as that of the centering hole 11c of the CD 300.Furthermore, at around the upper end portion of each of the elasticprojections 40b is provided a semi-cylindrical pawl section 40eprojecting outward. The distance L3 from the center axis of thesemi-cylindrical pawl section 40e to the CD receiving surface 40a ismade slightly greater than 1.2 mm. The distance L4 from the intersectionof the lower end of the pawl section 40e and the elastic projection 40bto the CD receiving surface 40a is set slightly smaller than 1.2 mm(i.e., L3>1.2 mm>L4). The magnetic member 41 is fixed to the upperperipheral portion of the centering hole 40c on the CD receiving surface40a.

The following describes the operation of the adapter having theabove-mentioned construction.

First, the elastic projections 40b are inserted into the centering hole11c in such a manner that the CD receiving surface 40a faces thelight-receiving surface 11b of the CD 300 as shown in FIG. 5 (b). Inthis procedure, since the outer diameter of the top end of the pawlsection 40e formed at an upper end portion of each elastic projection40b is slightly greater than the diameter of the centering hole 11c, theelastic projections 40b are elastically deformed inward when theprojections are inserted. When the projections are inserted until thelight-receiving surface of the CD 300 is put in contact with the CDreceiving surface 40a, the adapter 40 is completely attached to the CD300. In this state, the level of the center axis of the pawl section 40eis located above the level of the data recording surface 11a of the CD300, and the level of the intersection of the pawl section 40e and eachof the elastic projections 40b is positioned below the data recordingsurface 11a. In other words, the contact angle of the pawl section 40ewith respect to the upper peripheral edge of the centering hole 11c isdirected below the level, and the elastic projections 40b are kept in adeformed condition. Each of the elastic projections 40b having anelastic restoration force applies an elastic restoration force to thecentering hole 11c. Therefore, the elastic projections 40b press the CD300 downwardly against the CD receiving surface 40a by the operation ofthe pawl sections 40e. Thus, the adapter 40 and the CD 300 are rigidlysecured.

Then the adapter 40 is moved closer to the MD turntable 200 as shown inFIG. 5 (c). The adapter 40 has the magnetic member 41 fixed theretohaving the same construction as that of the magnetic member 2 of the MD100 and has the centering hole 40c formed therein having the samediameter as that of the centering hole 1c of the MD 100. Therefore, themagnetic member 41 is attracted to the magnet clamper 5 due to itsmagnetic force in the same manner as in the conventional example, andthe centering hole 40c is centered by the taper cone section 4. Thus,the lower contact surface 40d is put in contact with the upper surface3a of the disc receiving section 3 to completely clamp the CD 300 on theMD turntable 200.

In the condition where the clamping is completed, the height of the datarecording surface 11a is defined by the distance from the contactsurface 40a contacted with the disc receiving section 3 to the CDreceiving surface 40a. The position of the CD 300 in the direction ofthe plane of the disc is defined by the contact of the centering hole40c with the taper cone section 4, and by the contact of the pawlsection 40e with the centering hole 11c by the elastic restoration forceof the elastic projections 40b.

The distance from the upper surface 3a of the disc receiving section 3to the data recording surface 11a is approximately equal to the sum ofthe distance of 0.8 mm from the contact surface 40d to the CD receivingsurface 40a and the thickness 1.2 mm of the substrate 11, the sum being2.0 mm. The above value is equal to the distance of 2.0 mm from the discreceiving section 3 to the data recording surface 1a of the MD 100 as inthe description of the conventional example shown in FIGS. 8 (a) and 8(b).

The operation of clamping the MD 100 on the MD turntable 200 isperformed in the same manner as in the conventional example, andtherefore no description therefor is provided herein.

Although the present embodiment has substantially the same effect asthat of the second embodiment, the present embodiment requires no suchmeans as the CD clamper 30 in the disc apparatus. Therefore the presentembodiment has the great effect of allowing the CD to be clamped only byusing the MD turntable 200.

According to the present embodiment as described above, the adapter 40having a clamp mechanism including the same magnet clamp as that of theMD 100 is provided with the CD receiving surface 40a for receiving thelight-receiving surface 11b of the CD, the surface 40d to be put incontact with the disc receiving section 3 of the MD turntable 200, andthe elastic projections 40b each having the pawl section 40e at theirtip end portions for centering the CD 300 and pressing the CD againstthe CD receiving surface 40a, where the distance from the surface 40d tothe CD receiving surface 40a is made 0.8 mm. Thus, the adapter 40 havingthe CD 300 attached thereto can be clamped on the MD turntable 200.Furthermore, the distance from the data recording surface 11a of the CD300 to the upper surface 3a of the disc receiving section 3 is equal tothe sum of the thickness 0.8 mm of the adapter and the thickness 1.2 mmof the substrate 11, i.e., the sum 2.0 mm which is equal to the distancefrom the data recording surface 1a of the MD 100 to the disc receivingsurface 3a. Therefore, the data recording surface 1a and the datarecording surface 11a are put at an equal distance viewing from theoptical head to allow either of the discs of MD and CD to be read byusing a single optical head without any technical problem.

Although four elastic projections 40b each having a pawl section 40e arearranged at regular angular intervals of 90° in the present embodiment,it is also permitted to use any number of the elastic projections 40bprovided that at least three elastic projections 40b are arranged atapproximately regular angular intervals.

Although the elastic restoration force of the elastic projections 40beach provided with the pawl section 40e is used for pressing the CD 300against the CD receiving surface 40a to center the CD in the presentembodiment, any other centering method may be adopted.

Fourth Embodiment

The following describes an optical disc apparatus in accordance with afourth embodiment of the present invention with reference to theattached drawings.

The purpose of the present embodiment is to achieve an optical discapparatus which can at least play back the CD and the MD compatibly withuse of a single drive unit.

FIGS. 6 (a) and 6 (b) show an optical disc apparatus in accordance withthe fourth embodiment of the present invention, where FIG. 6 (a) shows aplan view, and FIG. 6 (b) shows a sectional view of the optical discapparatus. In each of FIGS. 6 (a) and 6 (b), right-hand rectangularcoordinate systems are defined as illustrated in the figures.

It is to be noted that the MD 100, MD turntable 200, CD 300, and CDturntable 400 are the same as those of the conventional examples.Regarding the MD turntable 200 and the CD turntable 400, the discreceiving section 3 of the MD turntable 200 is displaced by 0.8 mm fromthe disc receiving section 13 of the CD turntable 400 negatively in thez-axis direction. The MD turntable 200 is set sufficiently apart fromthe CD turntable 400 in the x-axis direction by such a distance that theCD 300 does not interfere with the MD turntable 200 when the CD 300 isloaded on the CD turntable 400. An MD spindle motor (M1) is providedwith an MD turntable having an MD disc receiving section at an end ofits rotary shaft; and a CD spindle motor (M2) is arranged so that itsrotary shaft is approximately in parallel with the rotary shaft of theMD spindle motor and provided with a CD turntable having a CD receivingsection at the rotary shaft end at which the MD turntable is provided.

It is assumed that the line X--X is a straight line in parallel with thex-axis that connects the center of the MD turntable 200 and the centerof the CD turntable 400. Reference numeral 51 denotes an objective lenswhich is arranged on the line X--X at the side of the light-receivingsurface of the MD 100 or the CD 300 and has at least a function ofapplying a laser beam onto the data recording surface of the MD 100 orthe CD 300. Reference numeral 50 denotes an optical head which isprovided with the objective lens 51 and has a function of executing atleast playback of the MD 100 and the CD 300 by generating a laser beamand leading the beam to the objective lens 51. Reference numeral 52denotes a pair of guide rails 52 of which an axial center is arranged inparallel with the line X--X. The guide rails 52 are slidably engagedwith the optical head 50 and have a length allowing the objective lens51 to access the data recording area of the MD 100 and the CD 300.Reference numeral 53 denotes a cartridge including therein the MD 100.

The following describes the operation of the optical disc apparatushaving the above-mentioned construction.

When the MD 100 is loaded on the MD turntable 200, playback of data canbe performed by conventional means by virtue of the fact that the guiderails 52 have a length sufficient for allowing the objective lens 51 tocover the data recording area of the MD 100. In the above case, thedistance from the disc receiving section 3 to the data recording surface1a of the MD 100 is 2.0 mm which is the same as in the conventionalexample. Assuming that the distance from the objective lens 51 to thedata recording surface 1a of the MD 100 is H3, the distance from theobjective lens 51 to the disc receiving section 3 is (H3-2.0) mm. In theabove case, the cartridge 53 including the MD 100 does not interferewith the CD turntable 400.

When the CD 300 is loaded on the CD turntable 400, the MD turntable 200does not interfere with the CD 300 because the MD turntable 200 isseparated apart from the CD 300 by a distance sufficient for avoidingmutual interference. The objective lens 51 moves along the line X--X,and therefore it accesses the CD 300 in the radial direction of thedisc. In the above case, the distance from the disc receiving section 13to the data recording surface of the CD 300 is 1.2 mm in the samearchitecture as in the description of the conventional example. However,the disc receiving section 13 of the CD turntable 400 is positionedhigher by 0.8 mm than the disc receiving section 3 of the MD turntable200 in the z-axis direction. Therefore, the distance from the objectivelens 51 to the disc receiving section 13 is L5-2.0+0.8=L5-1.2. For thereason that the distance from the disc receiving section 13 to the datarecording surface 11a of the CD 300 is 1.2 mm, the distance from theobjective lens 51 to the data recording surface 11a is L5-1.2+1.2=L5. Inother words, the data recording surface 1a of the MD 100 and the datarecording surface 11a of the CD 300 are put at an equal distance fromthe objective lens 51, and therefore the CD 300 can be subjected toplayback when the MD 100 can be played back.

According to the present embodiment as described above, by providing theMD turntable 200, the CD turntable 400, and the objective lens 51 whichmoves along the line that connects both the turntables, positioning bothturntables apart by a distance sufficient for avoiding interference ofthe CD 300 with the MD turntable 200 when the CD 300 is clamped on theCD turntable 400, and arranging the disc receiving section 3 of the MDturntable 200 in a position 0.8 mm below the disc receiving section 13of the CD turntable 400, the objective lens 51 can compatibly accesseither of the MD 100 or the CD 300 in the radial direction of the discs.Furthermore, the data recording surfaces 1a and 11a are put at an equaldistance from the objective lens 51, and therefore either of the discscan be subjected to data playback in the same condition.

Fifth Embodiment

The following describes an optical disc apparatus in accordance with afifth embodiment of the present invention with reference to the attacheddrawings.

The purpose of the present embodiment is to provide an optical discapparatus which can at least play back either of the CD and the MDcompatibly with use of a single drive unit.

FIG. 7 shows an optical disc apparatus in accordance with the fifthembodiment of the present invention.

The MD turntable 200 and the CD turntable 400 are the same as those ofthe conventional example. An optical head 68 and an objective lens 69have the same functions as those of the optical head 50 and theobjective lens 51 of the fourth embodiment though they have differentconfigurations. The objective lens 69 has its optical axis OA. Theoptical head 68 and the objective lens 69 move in the directionindicated by an arrow B in FIG. 7.

Reference numeral 70 denotes a base of the apparatus, reference numeral60 denotes a spindle motor having a rotary shaft 61 connected to therotor of the spindle motor 60. The spindle motor 60 rotates its rotaryshaft 61 forwardly and reversely, and stops the rotary shaft 61according to input signals. It is noted here that the forward rotationdirection of the MD turntable 200 is defined to be "forward", and thereverse rotation direction thereof is defined to be "reverse".

Reference numeral 62 denotes a pivot shaft which is arranged in parallelin the direction indicated by the arrow B as fixed to the stator of thespindle motor 60. One end of the pivot shaft 62 is connected to a motor65. The motor 65 rotates and stops the pivot shaft 62 according to aninput signal. The other end of the pivot shaft 62 is supported by apivot support member 63 which is composed of a radial bearing or thelike to pivotally support the pivot shaft 62 with respect to the base70. Reference numeral 64 denotes a condition detecting section 64 whichoptically detects the rotational position of the pivot shaft 62 withrespect to the base 70 to generate a detection signal. The conditiondetecting section 64 generates an MD setting completion signal when therotary shaft 61 of the spindle motor 60 is put in parallel with theoptical axis OA with the MD turntable 200 set in the upper position,while the condition detecting section 64 generates a CD settingcompletion signal when the rotary shaft 61 is put in parallel with theoptical axis OA with the CD turntable 400 set in the upper position.

Reference numeral 67 denotes a selection switch which outputs a signalfor selecting between playback of the MD and the playback of the CDaccording to the condition of the switch. Reference numeral 66 denotes acontrol section which receives a selection signal from the selectionswitch 67 and a signal from the condition detecting section 64 to supplya rotation signal and a stop signal to the motor 65 and supply a forwardrotation permission signal, a reverse rotation permission signal, and astop signal to the spindle motor 60 according to the inputs from theselection switch 67 and the condition detecting section 64. The controlsection 66 outputs a rotation signal to the motor 65 until an MD settingcompletion signal is input from the condition detecting section 64 whenthe MD selection signal is supplied from the selection switch 67. Whenthe motor 65 is rotating, the stop signal is continuously output to thespindle motor 60. Subsequently, when the MD setting completion signal isinput from the condition detecting section 64, the control section 66outputs the stop signal to the motor 65 and outputs the forward rotationpermission signal to the spindle motor 60. When a CD selection signal issupplied from the selection switch 67 to the control section 66, thecontrol section 66 outputs the rotation signal to the motor 65 until theCD setting completion signal is supplied from the selection switch 67.When the motor 65 is rotating, the stop signal is continuously output tothe spindle motor 60. Subsequently, when the CD setting completionsignal is input from the condition detection section 64, the controlsection 66 outputs the stop signal to the motor 65 and outputs thereverse rotation permission signal to the spindle motor 60.

The pivot shaft 62 has its center axis S arranged at an equal distancefrom the data recording surface of the MD and the data recording surfaceof the CD when the discs are clamped on their respective turntables asshown in FIG. 7.

The following describes the operation of the optical disc apparatushaving the above-mentioned construction.

First, when the MD is selected by the selection switch 67 to direct theMD turntable 200 upward as shown in FIG. 7, the selection switch 67outputs the MD selection signal to the control section 66, while thecondition detecting section 64 outputs the MD setting completion signalto the control section 66. Then the control section 66 outputs the stopsignal to the motor 65 and outputs the forward rotation permissionsignal to the spindle motor 60. When a play switch (not shown) ispressed in the above condition, the spindle motor 60 rotates forwardly.

Next, when the CD is selected by the selection switch 67 to direct theMD turntable 200 upward as shown in FIG. 7, the selection switch 67outputs the CD selection signal to the control section 66, while thecondition detecting section 64 outputs the CD setting completion signalto the control section 66. Then the control section 66 outputs therotation signal to the motor 65 and outputs the stop signal to thespindle motor 60. Thus the motor 65 rotates, and the pivot shaft 62connected to the motor 65 pivots around the axis S to pivot the spindlemotor 60 connected to the pivot shaft 62 around the axis S. When a playswitch (not shown) is pressed in the above condition, the motor shaft 61does not rotate because the stop signal is output to the spindle motor60.

Subsequently, when the CD turntable 400 is directed upward to make therotary shaft 61 of the motor put in parallel with the optical axis OA,the condition detecting section 64 outputs the CD setting completionsignal to the control section 66. The control section 66 outputs thestop signal to the motor 65 upon reception of the CD setting completionsignal and outputs the reverse rotation permission signal to the spindlemotor 60. When the play switch (not shown) is pressed at this time, thespindle motor 60 rotates reverse. Since the distance from the axis S tothe data recording surface of the MD is equal to the distance from theaxis S to the data recording surface of the CD, the distance from theobjective lens 69 to either of the discs is identical when either of theMD or CD is subjected to playback.

According to the present embodiment as described above, the optical discapparatus is provided with the reversible spindle motor 60 having at itsone end the MD turntable 200 and at its other end the CD turntable 400,the pivot shaft 62 which is fixed to the spindle motor 60 beingconnected at its one end to the motor 65 and supported by the pivotsupport member 63 on the base. The optical disc apparatus furthercomprises the condition detecting section 64 which detects the rotationangle of the pivot shaft 62, the selection switch 67 which selectsbetween the MD and the CD, and the control section 66 which outputssignals to the motor 65 and the spindle motor 60 based on the inputsignals from the selection switch 67 and from the condition detectingsection 64, where the center axis S of the pivot shaft 62 is put at anequal distance from the data recording surface of the MD and from thedata recording surface of the CD. Therefore, the MD and the CD can becompatibly driven by one spindle motor 60 in the optical disc apparatus,so that the data recording surfaces of the discs can be treated equallyviewing from the objective lens 69.

Although the present invention has been fully described by way ofexample with reference to the accompanying drawings, it is to be notedhere that various changes and modifications will be apparent to thoseskilled in the art. Therefore, unless such changes and modificationsotherwise depart from the scope of the present invention as defined bythe appended claims, they should be construed as included therein.

What is claimed is:
 1. An optical disc clamp mechanism for use in anoptical disk playback apparatus to selectively clamp a compact disc,having a compact disc centering hole of a first diameter, a compact discdata recording surface and a compact disc clamping surface spaced fromthe compact disc data recording surface by a first predetermined axialdistance, and a mini disc having a mini disc centering hole of a seconddiameter less than the first diameter, a mini disc data recordingsurface and a mini disc clamping surface spaced from the mini disc datarecording surface by a second predetermined axial distance greater thanthe first predetermined axial distance, said optical disc clampmechanism comprising:a mini disc turntable including a portion adaptedto be secured to a rotary shaft of a motor for rotation about a rotaryaxis, a mini disc receiving section for contacting the mini discclamping surface of the mini disc, and a mini disc centering mechanismfor centering the mini disc on said mini disc turntable; a compact discclamper rotatably mounted in facing relation to said mini disc turntablefor rotation about said rotary axis; and wherein said compact discclamper comprises: a compact disc receiving section for contacting thecompact disc data recording surface of the compact disc; a spacersection having a base end fixed to said compact disc receiving section,said spacer section extending from said base end toward said mini discturntable and being adapted to extend through the compact disc centeringhole of the compact disc, said spacer section having a contact surfaceat a distal end thereof for contacting said mini disc receiving sectionof said mini disc turntable; coupling means for coupling the compactdisc to said compact disc clamper so that the compact disc datarecording surface of the compact disc contacts said compact discreceiving section of said compact disc clamper, so that said spacersection extends through the compact disc centering hole of the compactdisc and so that the compact disc is centered on said compact discclamper; clamper centering means for contacting said mini disc centeringmechanism of said mini disc turntable and centering said compact discclamper relative to said mini disc turntable; and wherein said spacersection comprises a means for causing an axial distance from said minidisc receiving section of said mini disc turntable to the compact discdata recording surface of the compact disc, when the compact disc iscoupled to said compact disc clamper by said coupling means and saidcontact surface of said spacer section is contacted against said minidisc receiving section of said mini disc turntable, to be substantiallyequal to an axial distance from said mini disc receiving section of saidmini disc turntable to the mini disc data recording surface of the minidisc when the mini disc clamping surface is contacted against said minidisc receiving section.
 2. An optical disc clamp mechanism as recited inclaim 1, whereinthe second predetermined axial distance of the mini discwhich said optical disc clamp mechanism is adapted to clamp is greaterthan the first predetermined axial distance of the compact disc whichsaid optical disc clamp mechanism is adapted to clamp by 0.8 mm; and anaxial distance by which said contact surface of said spacer section isspaced from the compact disc when the compact disc is coupled to saidcompact disc clamper by said coupling means is 0.8 mm.
 3. An opticaldisc clamp mechanism as recited in claim 1, whereinthe secondpredetermined axial distance of the mini disc which said optical discclamp mechanism is adapted to clamp is greater than the firstpredetermined axial distance of the compact disc which said optical discclamp mechanism is adapted to clamp by an amount equal to an axialdistance by which said contact surface of said spacer section is spacedfrom the compact disc when the compact disc is coupled to said compactdisc clamper by said coupling means.
 4. An optical disc clamp mechanismas recited in claim 1, whereinsaid coupling means comprises at leastthree elastic members mounted to said spacer section and creating atleast three radially outwardly directed biasing forces.
 5. An opticaldisc clamp mechanism as recited in claim 1, whereinsaid spacer sectionis cylindrical and has at least three radially outwardly opening boresformed therein and spaced thereabout at approximately equal angularintervals; and said coupling means comprises a plurality of springsrespectively mounted in said bores.
 6. An optical disc clamp mechanismas recited in claim 5, whereinsaid coupling means further comprises aplurality of balls respectively mounted in said bores radially outwardlyof said springs.
 7. An optical disc clamp mechanism as recited in claim6, whereinball retaining pawl sections are formed about said bores at aperiphery of said spacer section to retain said balls, respectively; atip of a portion of each of said pawl sections located closest to saidcompact disc receiving section is spaced from said compact discreceiving section by less than the first predetermined axial distance;and said balls are positioned such that center lines therethrough whichare perpendicular to said rotary axis are spaced from said compact discreceiving section by greater than the first predetermined axialdistance.
 8. An optical disc clamp mechanism as recited in claim 1,whereinsaid clamper centering means comprises a hole in said spacersection having an axis along said rotary axis; and said hole comprisingsaid clamper centering means has a diameter substantially equal to thesecond diameter of the mini disc centering hole.
 9. An optical discclamp mechanism as recited in claim 1, whereinsaid compact disc clamperfurther comprises a magnetic member fixation surface; and a magneticmember is fixed to said magnetic member fixation surface of said compactdisc clamper so as to face said mini disc turntable.
 10. An optical discclamp mechanism for adapting a first type of optical disc for playbackin an optical disc apparatus arranged for playback of a second type ofoptical disc, where the first type of optical disc has a first centeringhole, a first data recording surface and a first clamping surface spacedfrom the first data recording surface by a first predetermined axialdistance, and where the optical disc apparatus has a turntable adaptedto clamp, against a disc receiving surface thereof, the second type ofoptical disc which has a second centering hole, a second data recordingsurface and a second clamping surface spaced from the second datarecording surface by a second predetermined axial distance greater thanthe first predetermined axial distance, said optical disc clampmechanism comprising:a disc clamper having means for receiving andretaining the first type of optical disc; a means for clamping said discclamper to the turntable of the disc playback apparatus; wherein saiddisc clamper comprises: a disc receiving section for contacting thefirst data recording surface of the first type of optical disc when thefirst type of optical disc is received and retained by said discclamper; and a spacer section which has a base end fixed to said discreceiving section, which has a distal end at which a contact surface isdefined for contacting the disc receiving surface of the turntable andwhich, when the first type of optical disc is received and retained bysaid disc clamper, protrudes through the first centering hole of thefirst type of optical disc such that said contact surface is spaced awayfrom the first clamping surface of the first type of optical disc by anaxial distance approximately equal to a difference between the firstpredetermined axial distance of the first type of optical disc and thesecond predetermined axial distance of the second type of optical disc.11. An optical disc clamp mechanism as recited in claim 10, whereinthefirst type of optical disc is a compact disc and the second type ofoptical disc is a mini disc; and said axial distance by which saidcontact surface is spaced away from the first clamping surface of thefirst type of optical disc is 0.8 mm.
 12. An optical disc apparatus foruse in selectively playing back a first type of optical disc having afirst centering hole, a first data recording surface and a firstclamping surface spaced from the first data recording surface by a firstpredetermined axial distance and a second type of optical disc having asecond centering hole, a second data recording surface and a secondclamping surface spaced from the second data recording surface by asecond predetermined axial distance greater than the first predeterminedaxial distance, said optical disc apparatus comprising:a turntable forclamping, against a disc receiving surface thereof, the second type ofoptical disc; and an optical disc clamp mechanism comprising: a discclamper having means for receiving and retaining the first type ofoptical disc; a means for clamping said disc clamper to said turntable;and wherein said disc clamper comprises a disc receiving section forcontacting the first data recording surface of the first type of opticaldisc when the first type of optical disc is received and retained bysaid disc clamper, and a spacer section which has a base end fixed tosaid disc receiving section, which has a distal end at which a contactsurface is defined for contacting said disc receiving surface of saidturntable and which, when the first type of optical disc is received andretained by said disc clamper, protrudes through the first centeringhole of the first type of optical disc such that said contact surface isspaced away from the first clamping surface of the first type of opticaldisc by an axial distance approximately equal to a difference betweenthe first predetermined axial distance of the first type of optical discand the second predetermined axial distance of the second type ofoptical disc.